ASTCA may borrow money and incur indebtedness, and may mortgage, assign, hypthecate and give security interest in ASTCA property and revenues to secure such indeptedness provided that such authority to borrow shall me limited to $4,250,000 from the American Samoa Government Employees' Retirement Fund, and no mortgage of or security interest in government land may be givenand provided that any indebtedness so created shall be that of ASTCA alone, and shall not be an obligation or debt of the government, unless otherwise provided by law.